The long range objective of this project is to study genetic exchange in streptococcus; primarily lysogenic conversion, transduction and transformation, and to determine how the acquisition of altered or new genetic material can affect some of the immunological and pathogenic characteristics of these organisms. At present we are investigating the identity and site of the genetic coding of an erythrogenic toxin produced by a rare non-lysogenic group A strain. Current findings verify the identity of the toxin and suggest that the genetic information may be found in a deficient prophage or in an integral segment of the streptococcal genome. Future studies will attempt to elucidate the genetic mechanism for the production of the three types of erythrogenic toxins in different toxinogenic strains.